Gear Tooth Contact Pattern Inspection

WARNING: This page is about a different car, the 2023 GMC Sierra 3500 HD and 2023 GMC Sierra 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

Pattern Evaluation (Ring Gear)

Drive Side Heel Toe	Pattern Condition	Coast Side Toe Heel	Pattern Condition	Corrective Action
Face Hobbing
Courtesy of GENERAL MOTORS COMPANY	Toe Contact	Courtesy of GENERAL MOTORS COMPANY	Heel Contact	Pinion shim correct. Increase backlash.
Courtesy of GENERAL MOTORS COMPANY	Desirable Pattern - Drive pattern should be centered on tooth	Courtesy of GENERAL MOTORS COMPANY	Desirable Pattern - Coast pattern should be center to slightly toe on tooth	No correction required.
Courtesy of GENERAL MOTORS COMPANY	Top Toe Contact	Courtesy of GENERAL MOTORS COMPANY	Top Heel Contact	Backlash correct. Increase in pinion shim.
Courtesy of GENERAL MOTORS COMPANY	Root Heel Contact	Courtesy of GENERAL MOTORS COMPANY	Root Toe Contact	Backlash correct. Decrease in pinion shim.
Courtesy of GENERAL MOTORS COMPANY	Top Heel Contact	Courtesy of GENERAL MOTORS COMPANY	Top Toe Contact	Pinion shim correct. Decrease backlash.
Courtesy of GENERAL MOTORS COMPANY	Root Toe Contact	Courtesy of GENERAL MOTORS COMPANY	Root Heel Contact	Pinion shim correct. Increase backlash.
Face Milling
Courtesy of GENERAL MOTORS COMPANY	Desirable Pattern - Drive pattern should be centered on tooth	Courtesy of GENERAL MOTORS COMPANY	Desirable Pattern - Coast pattern should be center to slightly toe on tooth	No correction required.
Courtesy of GENERAL MOTORS COMPANY	Top and Slightly Heel Contact	Courtesy of GENERAL MOTORS COMPANY	Top and Slightly Toe Contact	Backlash correct. Increase in pinion shim.
Courtesy of GENERAL MOTORS COMPANY	Root and Slightly Toe Contact	Courtesy of GENERAL MOTORS COMPANY	Root and Slightly Heel Contact	Backlash correct. Decrease in pinion shim.
Courtesy of GENERAL MOTORS COMPANY	Heel Contact	Courtesy of GENERAL MOTORS COMPANY	Toe Contact	Pinion shim correct. Decrease backlash.

Drive Side Heel Toe	Coast Side Toe Heel	Pattern Condition	Corrective Action
If the pinion depth needs to be adjusted, refer to Pinion Depth Adjustment . If the backlash needs to be adjusted, refer to Backlash Inspection and Adjustment .
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side Centered - Coast Side Centered	No correction required.
Drive Pinion Issue - 2-Cut Gearset
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side Low Heel Contact - Coast Side High Heel Contact	Inspect the backlash to ensure that it is approximately 0.08 - 0.13 mm (0.003 - 0.005 in) If backlash is correct, move the drive pinion closer to the ring gear by increasing the thickness of the pinion shim on a one-piece axle housing or by decreasing the thickness of the pinion shim on the 10.5 inch two-piece axle housing.
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side Low Heel Contact - Coast Side Low Toe Contact	Inspect the backlash to ensure that it is approximately 0.08 - 0.13 mm (0.003 - 0.005 in). If backlash is correct, move the drive pinion away from the ring gear by decreasing the thickness of the pinion shim on a one-piece axle housing or by increasing the thickness of the pinion shim on the 10.5 inch two-piece axle housing.
Backlash Issue
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side High Heel Contact - Coast Side High Toe Contact	Backlash incorrect. The ring gear is too far away from the drive pinion. Inspect and adjust the backlash as necessary to ensure that it is approximately 0.08 - 0.13 mm (0.003 - 0.005 in).
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side Low Toe Contact - Coast Side Low Heel Contact	Backlash incorrect. The ring gear is too close to the drive pinion. Inspect and adjust the backlash as necessary to ensure that it is approximately 0.08 - 0.13 mm (0.003 - 0.005 in).
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side Centered - Coast Side Centered	No correction required.
Drive Pinion Issue - 5-Cut Gearset
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side High and Slightly Heel Contact - Coast Side High and Slightly Toe Contact	Inspect the backlash to ensure that it is approximately 0.08 - 0.13 mm (0.003 - 0.005 in). If backlash is correct, move the drive pinion closer to the ring gear by increasing the thickness of the pinion shim on a one-piece axle housing or by decreasing the thickness of the pinion shim on the 10.5 inch two-piece axle housing.
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side Low and Slightly Heel Contact - Coast Side High and Slightly Toe Contact	Inspect the backlash to ensure that it is approximately 0.08 - 0.13 mm (0.003 - 0.005 in). If backlash is correct, move the drive pinion away from the ring gear by decreasing the thickness of the pinion shim on a one-piece axle housing or by increasing the thickness of the pinion shim on the 10.5 inch two-piece axle housing.
Backlash Issue
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side Heel Contact - Coast Side Toe Contact	Backlash incorrect. The ring gear is too far away from the drive pinion. Inspect and adjust the backlash as necessary to ensure that it is approximately 0.08 - 0.13 mm (0.003 - 0.005 in).
Courtesy of GENERAL MOTORS COMPANY	Courtesy of GENERAL MOTORS COMPANY	Drive Side Toe Contact - Coast Side Heel Contact	Backlash incorrect. The ring gear is too close to the drive pinion. Inspect and adjust the backlash as necessary to ensure that it is approximately 0.08 - 0.13 mm (0.003 - 0.005 in).